Originally elected as a Liberal, he became part of the Saskatchewan Party caucus in 1997. In April 1998, Gantefoer was a candidate for the Saskatchewan Party leadership, but was defeated on the second ballot by Elwin Hermanson. After the Saskatchewan Party"s victory in the 2007 election, he was appointed Minister of Finance and Government House Leader.
Gantefoer announced in February 2010 that he has been diagnosed with Parkinson"s disease, and later announced that he would not run in the 2011 election.
He was shuffled out of cabinet on June 29, 2010.